Liquid phase isomerization process integration

Abstract

Processes and apparatuses for producing a C 8 aromatic isomer product are provided. The process comprises introducing a reformate stream comprising aromatic hydrocarbons to a reformate splitter column to provide a plurality of streams. One or more streams comprising at least one stream from the plurality of streams is passed to a reformate upgrading unit to obtain an upgraded reformate stream. The upgraded reformate stream is passed to an aromatics stripper column to provide an aromatics stripper sidedraw stream comprising C 8 aromatic hydrocarbons. The aromatics stripper sidedraw stream is passed to a xylene separation unit to provide the C 8 aromatic isomer product and a raffinate product stream. At least a portion of the raffinate product stream is processed in a liquid phase isomerization unit to obtain an isomerized stream.

The invention claimed is: 
     
       1. A process for producing a C 8  aromatic isomer product from a reformate stream, wherein the process comprises:
 (a) introducing a reformate stream comprising aromatic hydrocarbons to a reformate splitter column to provide a reformate splitter bottoms stream comprising C 8+  aromatic hydrocarbons, a reformate splitter sidedraw stream comprising C 8  aromatic hydrocarbons, and a reformate splitter overhead stream comprising C 7−  aromatic hydrocarbons; 
 (b) subjecting at least the reformate splitter sidedraw stream to reformate upgrading conditions in a reformate upgrading unit to convert a portion of ethylbenzene to obtain an upgraded reformate stream, wherein the reformate upgrading unit and a transalkylation unit share a common compressor; 
 (c) passing the upgraded reformate stream to an aromatics stripper column to provide an aromatics stripper sidedraw stream comprising C 8  aromatic hydrocarbons and an aromatics stripper bottoms stream; 
 (d) passing the aromatics stripper sidedraw stream to a xylene separation unit to provide the C 8  aromatic isomer product and a raffinate product stream comprising C 8  aromatic isomers; 
 (e) contacting at least a first portion of the raffinate product stream with an isomerization catalyst in an isomerization unit in liquid phase at isomerization conditions in the absence of hydrogen to obtain an isomerized stream; 
 (f) passing at least a first portion of the isomerized stream to the xylene separation unit; 
 (g) passing at least a second portion of the isomerized stream to the aromatics stripper column; 
 (h) passing the aromatics stripper bottoms stream and the reformate splitter bottoms stream to an aromatics rerun column to provide an aromatics rerun column overhead stream comprising C 8  aromatic hydrocarbons including ethylbenzene; and 
 (i) passing the aromatics rerun column overhead stream and a second portion of the raffinate product stream to the reformate upgrading unit. 
 
     
     
       2. The process of  claim 1  further comprising:
 passing the reformate splitter overhead stream to an aromatics-extraction step to produce an aromatics extract stream comprising benzene and toluene, and 
 passing the aromatics extract stream to a fractionation step to provide a benzene product stream and a toluene enriched stream. 
 
     
     
       3. The process of  claim 2  further comprising passing the toluene enriched stream and an aromatics rerun column sidedraw stream rich in C 9  and C 10  alkylaromatics from the aromatics rerun column to the transalkylation unit. 
     
     
       4. The process of  claim 1  wherein the aromatics stripper column is divided wall column. 
     
     
       5. The process of  claim 1  wherein the xylene separation unit is a simulated moving bed adsorption unit. 
     
     
       6. The process of  claim 5  wherein the xylene separation unit uses a desorbent with a lower boiling point than the C 8  aromatic isomers. 
     
     
       7. The process of  claim 6  wherein the desorbent is toluene. 
     
     
       8. The process of  claim 1  wherein the C 8  aromatic isomer product is one of para-xylene or meta-xylene. 
     
     
       9. A process for producing a C 8  aromatic isomer product from a reformate stream, wherein the process comprises:
 (a) introducing a reformate stream comprising aromatic hydrocarbons to a reformate splitter column to provide a reformate splitter bottoms stream comprising C 8+  aromatic hydrocarbons, a reformate splitter sidedraw stream comprising C 8  aromatic hydrocarbons and a reformate splitter overhead stream comprising C 7−  aromatic hydrocarbons; 
 (b) subjecting the reformate splitter sidedraw stream to reformate upgrading conditions in a reformate upgrading unit to convert a portion of ethylbenzene to obtain an upgraded reformate stream, wherein the reformate upgrading unit and a transalkylation unit share a common compressor; 
 (c) passing the upgraded reformate stream to an aromatics stripper column to provide an aromatics stripper sidedraw stream comprising C 8  aromatic hydrocarbons and an aromatics stripper bottoms stream, wherein the aromatic stripper column comprises a divided wall column; 
 (d) passing the aromatics stripper sidedraw stream to a xylene separation unit to provide the C 8  aromatic isomer product and a raffinate product stream comprising C 8  aromatic isomers; 
 (e) contacting at least a first portion of the raffinate product stream with an isomerization catalyst in an isomerization unit in liquid phase at isomerization conditions in the absence of hydrogen to obtain an isomerized stream; 
 (f) passing the aromatics stripper bottoms stream and the reformate splitter bottoms stream comprising C 8+  aromatic hydrocarbons to an aromatics rerun column; 
 (g) passing a bottoms stream from the aromatics rerun column to a heavy aromatics column; 
 (h) passing a first portion of the isomerized stream to the xylene separation unit; and 
 (i) passing a second portion of the raffinate product stream and an aromatics rerun column overhead stream comprising C 8  aromatic hydrocarbons to the reformate upgrading unit. 
 
     
     
       10. The process of  claim 9  further comprising:
 passing the reformate splitter overhead stream to an aromatics-extraction step to produce an aromatics extract stream comprising benzene and toluene, and 
 passing the aromatics extract stream to a fractionation step to provide a benzene product stream and a toluene enriched stream. 
 
     
     
       11. The process of  claim 10  further comprising passing the toluene enriched stream and an aromatics rerun column sidedraw stream rich in C 9  and C 10  alkylaromatics from the aromatics rerun column to the transalkylation unit.